The fourth series of Merlin averaged 1.7 million viewers for Syfy in 2012, with a rating of 0.5m in the key 18-49 demographic. The numbers were up from series three's 2011 airing, which only managed an average of 1.5m.

Merlin's fifth series currently airs on BBC One in the UK - the series continues this Saturday (November 24) at 8pm with 'The Hollow Queen'.